Classic

iTrader: (3)

I just wanted to post up a quick thanks to everyone/anyone with the VE table ideas. Let me tell you - wow what a difference. My car ran pretty well for a big cam car (I thought), but after I installed my new adjustments (scaling the VE table 1200rpm and below) my car runs like a dream. On both cold and hot starts my car fires right up and holds an idle at 800 rpm or more - no more of this 1100rpm, 200rpm, 1100rpm, 3000rpm up and down BS that it used to do for a few seconds.

It still is a little rich at idle, but nothing like it was before. Now its time to hit the dyno for some wideband tuning.

Cal

iTrader: (1)

Yeah pretty amazing, huh? I ended up with the 50-60-70 setting and mine's doing better than ever now also. Now if we could just get a little more timing when the engine is cold . . .

oOoLy

I'm new user in the ls1-edit and i want to do the VE table adjustment, so i need your help ...... !

Thanks
Adnan

Cal

iTrader: (1)

Load LS1edit, open your current flash file, go to Edit, Engine Cal, Fuel Tab, click on Main Volumetric Efficiency, highlight the entire 400 rpm column, and scale by 50%, apply changes. Then scale the 800 column by 60%, and the 1200 column by 70%. Apply Changes, save to a new file name, then open LS1prog and flash your PCM.

oOoLy

Thank you Cal ....

What other tuning can i do with it ?

I want some books for ( LS1-Edit )

Thanks
Adnan

Cal

iTrader: (1)

http://ls1edit.slowcar.net/tuning.html

gillbot

iTrader: (27)

Is there a certain parameter we are shooting for when we tweak these numbers? I thought it was to narrow the injector pulse width but later heard this wasn't the case. Any ideas? I'd like to fine tune mine in better since I just used 60% from 400-1200.

Cal

iTrader: (1)

You can look at the injector pulse width, should be 3-4 ms. But the most reliable system I've found is my nose and seat of my pants . . . if it stinks, it's rich; if it stumbles when I punch it, it's lean. The problem is there is some kind of software "acelerator pump" that you are also affecting by changing the VE.

gillbot

iTrader: (27)

Not sure I follow... Is this something that can be damaging later? Something that should be checked if the table has been tweaked?

NoGo

iTrader: (2)

The VE table is used in determining the minimum amount of fuel necessary to keep the car running at that RPM.

Once the base pulswidth is known then car starts adding in all of the other math, load, performance, emmissions, to adjust the cars fueling.

The Accellerator pump that Cal is talking about is the "tip in" richness that is required to give your car the kind of throttle response you want and stop the car from stumbling with sudden load changes.

When you hammer the throttle your throttlebody opens up and the density of the air inside the manifold changes to atmospheric. Your car is suddenly ingesting air that is much more dense (read more oxygen) than it was previously. To keep up with this sudden addition of oxygen and make the most of it your car uses a "tip in" or "accelerator pump" calculation to suddenly change how much fuel is added to accomodate the additional oxygen.

The accelerator pump calculation is based on volumetric efficiency (or speed density). It uses the predetermine correction factors that we see on the VE table to determine the exact amount of oxygen that the car just ingested. If you have reduced the VE table by a significant amount, the accelerator pump function will not add adequate fuel to deal with the sudden influx of air. The result is that the car stumbles or bogs when you stab the throttle.

Adjusting the VE table is like everything else. As long as you don't go wild, you will be fine.

Good Luck,
Kevin

gillbot

iTrader: (27)

I went by the initial recommendation of multiply by 60% for all cells 400-1200. Lately people are recommending varios different combinations. I am just wondering what is the "proper" way to tune for this. What parameters should be monitored to get it dialed in correctly instead of all the educated guesses I see floating around.

NoGo

iTrader: (2)

I think Cal nailed the "proper" way.

How much you shift the table is going to be different for every car.

gillbot

iTrader: (27)

Then I'd have to tune for injector pulse width? My car pretty much always stinks since I have an ORY and it hasn't been dyno tuned for the cam yet. I'm just trying to be sure I dial in the lower end as close as possible.

EVIL

when i started tweaking my ve, i would make a small change, then hook up efi live, and go for a spin. i have 2 routes i take, and try to maintain the same driving style on each and see what i end up with.

ve made a huge difference in the few cars that i have tuned for drivability. still havent had a chance to tune on the dyno yet since i am just trying to get the OEM drivability back first.

gMAG

iTrader: (1)

Great thread! Thanks, everyone.

Darkhalf

iTrader: (1)

Just to let everyone know. My car has been having problems with Cold starts once I drive off and come to a stop about 3 blocks down the street it will go down to 400rpms then back up to 1000 rpms, it does this all the time until it is up to normal operating temps then it kind of goes away. I first multiplied the 400-1200 by 80% had little to no effect. I then did the 50-60-70. That was a no no for my car, so goes to show that all cars are not the same. When I came to a stop it would just sit at 400 rpms and wouldn't go up at all. So its putting a lot of air in but no fuel. I then went back to stock and then adjusted by multi by 70% 400-1200 rpms seems to be a lot better for now, but I might need to adjust IACs a little bit. The other problem that I have is the bucking issues at around 1500 rpms. I noticed when I did the 70% it helped a little bit, but its still there. Any help would be appreciated thanks. BTW Great thread too and Cal for his tips

gillbot

iTrader: (27)

Well, after more miles on the 60% VE tune for 400-1200, the car has reverted back to it's stalling and surging with hot starts and seems to be getting worse.

Any Ideas now?

ChrisB

How much time do you spend driving in the 400-1200 range? Assuming the tables are indexed correctly you should only have a change in that range.

Now if your l-trims are different and are carrying over a bit that could cause a problem, but it should still only be for a bit untill you move into a new cell.

What it boils down to is that your O2's are fixing your part throttle a/f ratio. Do you have splits between your two sides - is it possible you have an exhaust leak anywhere?

Try resetting your computer and seeing if the fix holds for awhile again - if it does it is almost certainly your o2's initiating a fueling change. Have your l-trims/s-trims changed at all?

gillbot

iTrader: (27)

Haven't logged the L-trims, I thought they were useless at that low of a range.

Suprisingly, with the 2.73 gear I spend alot of time in the 1000-1200 rpm range which I believe adds to the problems. Around town cruising the car stays pretty near 1000 rpm untill I get on the highway or something. Maybe I need to tweak my shift tables to hold it higher before it shifts to the next gear?

RPM WS6

iTrader: (3)

I am still having issues as well after a lot of VE table tuning. My issues are centered around coming to a stop though. The car goes into "surge mode" when it downshifts during normal stopping. As soon as I come to a complete stop, it idles perfect. The catch is, sometimes it stops perfect I have it to a point where both cold and warm starts seem to be good at the moment (knock on wood).

My Ltrims are elevated and split at idle, (about +13.3 and +7.8) not sure why they are split but they pretty much even out as I drive. Strims are good (and even).

Do you think Ltrims are my issue? I have messed with all kinds of IAC changes and many different VE table chnages in the 400-1200 range and I'm getting frustrated again. I was gonna try raising the idle some, but I don't think that will help any (idle is at 800rpm in P & D).

Should I try adjusting my IFR table to bring down the Ltrims a little? Would that have an effect on my intermittent surge while stopping issue?